Исследование зависимости прочностных характеристик металла от вариаций режимов техпроцессов изготовления с использованием микроструктурно-чувствительных акустических параметров

The microstructure-sensitive acoustic parameters (MSA parameters) of metal of the object under control are determined using measurements of the propagation time of bulk elastic waves of the ultrasonic range by the echo-pulse method. The structural features of the metal are thus evaluated not only in the surface layer, but also throughout the entire volume. We present the results of practical application of the MSA-parameters to estimation of the deviation of the velocity ratios of longitudinal and shear waves relative to the «basic» state with known strength characteristics. A correlation of the MSA-parameters with variations in the elastic moduli of metals attributed to modification of their microstructure is discussed. The generalized values of the ratios of wave velocities for steels of the same group are used in calculations to characterize the «base» state. It is shown that when calculating the MSA-parameters for a certain kind of construction steel, it is possible to use the averaged ratios of the velocities measured for quasi-isotropic reference samples made of the same type of steel. The generalized baseline ratios of the longitudinal and shear wave velocities are determined for the samples made of carbon steel, low-alloy, and alloyed steels. We present experimental evidence of using MSA-parameters to detect microstructural changes in metal samples and accompanying changes in their strength characteristics that occur during changes in modes and conditions of welding and heat treatment. A comparative analysis of the MSA parameters with the values of the mechanical properties and parameters of the crack resistance of the metal is carried out. It was shown that the accuracy of measuring the MCA parameters provided by modern hardware significantly exceeds changes in them occurred under significant deviations of the strength characteristics. The experimental results obtained clearly indicate that the MSA-parameters can be successfully used to improve the methods of quantitative non-destructive assessment of the features of metal microstructures